[unreadable] Renin-synthesizing cells are known to be crucial in the regulation of blood pressure and fluid and electrolyte homeostasis. These cells have been considered as terminally differentiated because they synthesize a hormone (renin), are few in numbers, and are restricted to a juxtaglomerular localization in the adult mammalian kidney. Recently, however, we showed that renin cells are precursors for multiple renal and extrarenal cell types. Although it has been accepted that renin cells derive from the mesoderm, our preliminary work indicates that either a subset or all of the renin-expressing cells may derive from ectoderm. We further hypothesize that renin is necessary for the differentiation of ectodermal precursors into their derivative tissues (i.e. skin, choroid plexus, sympathetic ganglia, adrenal medulla and head cartilage). To define whether renin-expressing cells derive from neuroectodermal or neural crest cells we will use available mouse models that mark cells derived from the neuroectoderm, the neural crest and the renin cell lineage. To determine whether deletion of the renin gene in neuroectodermal/neural crest/ epidermal precursors results in defective development of their derivative tissues, we will generate a renin-floxed mouse and will cross it with mice expressing ere recombinase in precursors of neuroectoderm (nestin-cre), neural crest cells (wnt1-cre) and epidermis (K14-cre). [unreadable] The proposed studies should generate fundamental new knowledge on renin cell specification and neural/ectodermal development. Furthermore, the generation of a renin-floxed mouse will be a valuable tool to solve the long standing controversy regarding the role of locally generated renin versus circulating renin. This work has the potential to open new avenues for the understanding, prevention and treatment of hypertension, birth defects and kidney diseases. [unreadable] [unreadable]